A communication network is mainly composed of terminals, base stations, and a core network. The base station implements the functions such as data transfer, resource management and control, etc., for terminals accessing this base station within its coverage area. The base station and terminals serviced by the base station construct a system. The base station may communicate with a terminal via a wired connection, or a wireless connection, and one base station may provide services for multiple terminals. Typically, the topology between the base station and the terminals is point-to-multipoint. In other words, the terminals serviced by the same base station usually exchange information via the base station, rather than communicate with each other directly. As illustrated in FIG. 1, it is a schematic diagram of a network with a point-to-multipoint topology in the conventional art. The topology between the base station and terminals may also be a mesh architecture, and in this case the terminals serviced by the same base station may communicate with each other directly.
Generally, a base station receives only uplink signals transmitted from the terminals serviced by the base station, and does not receive an uplink signal transmitted from a terminal serviced by a neighboring base station. The base stations generally communicate with each other via a wired connection in a backbone network, without occupying the air interface resources. However, in some special occasions, the base station may require a terminal serviced by itself to transmit an uplink signal to a neighboring base station. For example, when the backbone network breaks down, two base stations may communicate with each other by a terminal within the common coverage area. In this case, this terminal serves as a relay station between the two base stations/systems. For a further example, in a cognitive radio system, a base station may require a terminal serviced by the base station to transmit some necessary cognitive signals, such as a base station identification (ID), a terminal ID, etc., to a neighboring base station, so as to determine an interfering neighboring base station and perform corresponding interference negotiation.
In the conventional art, the inter-system communication by a terminal being relayed is performed as follows.
1. The base station (referred to as serving base station hereinafter) providing services for the terminal that implements the relay function (referred to as a relay terminal hereinafter) transmits the information to be relayed to the relay terminal, and allocates relay signal transmission resources for the relay terminal at the same time. The relay signal transmission resources may include a time and frequency resource for transmission, the encoding and modulation schemes, and the transmit power, etc.
2. Upon receiving the information to be relayed (referred to as relay information hereinafter), the relay terminal transmits the relay information to the neighboring base station directly via the allocated time and frequency resource; after the relay information is transmitted, the relay terminal does not determine whether the relay information has been correctly received by the neighboring base station, either.
The inventors discover that in the conventional art described above, because, and the relay terminal is generally located at the edge of the coverage area of the neighboring base station, which suffers significant channel attenuation, the probability of receiving the relay information correctly by the neighboring base station is very low. In addition, because the transmission location, and modulation and encoding methods used for the relay terminal to transmit the uplink signal are allocated by the serving base station, the neighboring base station is unable to know where to receive and how to demodulate and decode the uplink signal from the relay terminal.